Linkage for a reciprocating engine crankshaft

ABSTRACT

A connecting linkage between a piston and a crank pin of a crankshaft in a reciprocating engine comprises a crank pin extension link pivotally connected at one end to the piston rod and pivotally connected at the other end to the crank pin. A toggle arm, which is longer than the crank pin extension link, pivots at one end about a stationary pivot point, and is pivotally connected at the other end to the point of connection between the piston rod and crank pin extension link. The toggle linkage drives the crank pin through an arc of substantially more than 180* during the power stroke of the piston, and applies a tangential thrust to the crank pin during a substantial portion of the power stroke of the piston.

United States yatent Garman 1 Sept. 26, 1972 [54] LINKAGE FOR ARECIPROCATING ENGINE CRANKSHAFT [72] Inventor: Wilbur G. Garman, 349 E.16th St.,

San Bernardino, Calif. 92404 [22] Filed: Aug. 3, 1970 [21] Appl. No.:60,356

Related U.S. Application Data [63] Continuation-in-part of Ser. No.758,532, Sept.

9, 1968, Pat. No. 3,568,416.

[52] U.S. Cl. ..74/38, 123/197 AB, 74/520 [51] Int. Cl ..F16h 21/26 [58]Field of Search ..74/38, 39, 40, 520;

123/197 AC, 197 AB, 197 R [56] References Cited UNITED STATES PATENTS2,295 10/1841 Johnson ..74/38 1,784,431 12/1930 Green ..74/38 FOREIGNPATENTS OR APPLICATlONS 2,704 2/1899 Great Britain ..74/38 PrimaryExaminer-William F. ODea Assistant Examiner-Wesley S. Ratliff, Jr.Attorney-Christie, Parker & Hale [57] I ABSTRACT A connecting linkagebetween a piston and a crank pin of a crankshaft in a reciprocatingengine comprises a crank pin extension link pivotally connected at oneend to the piston rod and pivotally connected at the other end to thecrank pin. A toggle arm, which is longer than the crank pin extensionlink, pivots at one end about a stationary pivot point, and is pivotallyconnected at the other end to the point of connection between the pistonrod and crank pin extension link. The toggle linkage drives the crankpin through an arc of substantially more than 180 during the powerstroke of the piston, and applies a tangential thrust to the crank pinduring a substantial portion of the power stroke of the piston.

6 Claims, 11 Drawing Figures LINKAGE FOR A RECIPROCATING ENGINECRANKSHAFT CROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of my application, Ser. No.- 758,532, filed Sept.9, 1968, now Pat. No. 3,568,416.

BACKGROUND OF THE INVENTION This invention relates to a linkage forconnecting a piston to the crank pin of a crankshaft, and moreparticularly to a toggle arm in combination with a piston rod and acrank pin extension link for improving the effective application ofthrust transmitted to the crankshaft during the power stroke of thepiston.

Conventional internal combustion engines, such as diesel and automobileengines, have long used a piston rod and crank pin as the linkagebetween the piston and crankshaft. Although of proven value, thislinkage does not efficiently convert translational motion of the pistoninto rotational motion of the crankshaft. Piston thrust in conventionalengines is effectively transmitted to the crankshaft during theintermediate portion of the power stroke, but there is substantial lostmotion in the piston travel during the beginning and end portions of thepower stroke. The greatest thrust is available in the cylinders ofconventional engines at the beginning of the power stroke, but theconventional linkage does not effectively transmit this thrust to thecrankshaft.

SUMMARY OF THE INVENTION Briefly, this invention includes a linkage forconnecting a piston with the crank pin of a crankshaft in areciprocating engine. The linkage includes a piston rod pivotallysecured to the piston, a crank pin extension link which is pivotallysecured at one end to the piston rod and at the other end to the crankpin. The extension link has a length greater than the radius of thecrank pin throw and less than the diameter of the crank pin throw. Atoggle arm, which is longer than the crank pin extension link, ispivotally secured at one end to the pivotal connection between thepiston rod and crank pin extension link. The other end of the toggle armis secured to a stationary pivot point which is located so that thetoggle arm transmits force between the piston and the crank pin throughthe piston rod and crank pin extension link in a substantiallytangential direction to the crankshaft during a substantial portion ofthe power stroke of the piston. The linkage also drives the crank pinand the crankshaft through more than one-half a revolution during thepower stroke of the piston.

In one form of the invention, the toggle arm, crank pin extension link,and piston rod are mutually connected by a single wrist pin. Thelocation of the mutual pivot point is determined by positioning of thefixed end of the toggle arm at a point so that the crank pin extensionlink travels in a substantially tangential relation to the crankshaftduring the beginning and end portions of the power stroke of the piston.Thus, the force exerted by the piston during its motion in the cylinderis effectively transmitted to the crankshaft during the portions of thepower stroke in which piston thrust is least effectively transmitted tothe crankshaft in conventional engines.

The stationary pivot point of the toggle arm may be located on eitherside of the crankshaft to apply tangential force to the the crank pinand drive the crank pin through more than of rotation during the powerstroke of the piston. However, the toggle action of the crank pinextension link is more pronounced during particular portions of thepiston travel, depending upon which side of the crank shaft the togglearm pivot point is located. One side may be more advantageous than theother, depending upon the type of fuel used, for example.

The piston rod is preferably longer than the crank pin extension link.The length of the piston rod, however, is not critical, and can bevaried to reduce side thrust on the piston to thereby reduce frictionalpower loss. For example, a long piston rod can be used to reduce sidethrust on the piston without lengthening the stroke. The toggle arm ispivotally connected to the crank pin extension link and piston rod andextends to a point adjacent and crankshaft, where it is pivotallysecured to the engine block. The toggle arm is of such length that thecrank pin extension link is maintained in a tangential relation to thecrankshaft during a substantial portion of the power stroke of thepiston, a preferred length being more than the diameter of the crankthrow. Preferably, the length of the toggle arm is about 1% times thediameter of the crank throw, and the extension link preferably has alength of about fiveeighths the diameter of the crank throw.

During the portion of the piston travel when the piston is near bottomdead center, latent inertial energy is converted by the toggle linkageto tangential thrust which carries the crank pin through substantiallymore than 180 of rotation during the power stroke of the piston so as topermit scavenging, breathing, or similar operations to be performedwithin the cylinder. Upon further rotation of the crankshaft, the crankpin extension link exerts a force on the mutual pivot point of thepiston rod, toggle arm, and crank pin extension link that rapidlyreturns the piston to its top dead center position. The rapid return ofthe piston is of particular value in diesel engines and the like, whererapid compression is essential to operation of the engine.

The toggle arm, crank pin extension link, and piston rod, can beconnected to each other at more than a single pivot point. For example,a double wrist pin arrangement can be used to connect the piston rod andcrank pin extension link, and to separately connect the toggle arm tothe crank pin extension link at a point adjacent to its connection tothe piston rod. This configu ration produces a walking beam action onthe crank pin which applies tangential force to the crank pin prior towhen the piston reaches top dead center during its travel. The walkingbeam action blends into a'toggle action which applies a tangential forceto the crank pin through a substantial portion of the pistons powerstroke. The toggle action blends into a walking beam action prior tobottom dead center position of the piston to apply a tangential force tothe crank pin through end portion of the power stroke of the piston.Thus, the linkage transmits thrust to the crank pin through top deadcenter and bottom dead center positions of the piston, which are theportions of the piston travel during which piston thrust is leasteffectively transmitted to the crankshaft in conventional engines.

The linkage of this invention can be employed in any reciprocatingengine, including any number of pistons. It is adaptable for use withpunch presses, cutting machinery, conveying machinery, and the like, aswell as with internal combustion engines. The linkage can also beemployed in engines wherein force is exerted on a piston by the actionof expanding vapors, gases, steam, or hydraulic fluid. Because of thehigh efficiency obtained by the linkage, it is particularly valuable foruse with two or four-cycle internal combustion engines.

The linkage of this invention is particularly useful in diesel engines,where air or other gases are compressed to a temperature which issufficiently high to ignite fuel injected into the cylinders. Similarly,in refrigeration machinery, rapid heat transfer can be obtained by usingthe linkage, where the temperature is raised by the heat of compressionof the apparatus. In these types of machinery, the compression stroke isof crucial importance, since rapid compression of the gases is essentialto satisfactory operation of the engines. The linkeage described hereinis useful in these types of machinery because of the high speedcompression stroke it produces.

BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects of theinvention will be more fully understood by referring to the followingdetailed description and the accompanying drawings, in which:

FIG. 1 is an elevation showing the toggle linkage at the beginning ofthe power stroke of the piston;

FIG. 2 is an elevation showing the linkage of FIG. 1 when the pistonnears the end of the power stroke;

FIG. 3 is an elevation showing the linkage of FIG. 1 during the returnstroke of the piston;

FIG. 4 is an elevation showing an alternative configuration of thetoggle linkage of FIG. 1 at the beginning of the power stroke of thepiston;

FIG. 5 is an elevation showing the toggle linkage of FIG. 4 during thereturn stroke;

FIG. 6 is an elevation showing an alternative toggle linkage in which adouble wrist pin arrangement connects the piston rod, toggle arm, andcrank pin extension link, and in which the linkage is shown at thebeginning of the power stroke of the piston;

FIG. 7 is an elevation showing the linkage of FIG. 6 with the pistonjust past top dead center during the power stroke;

FIG. 8 is an elevation showing the linkage of FIG. 6 when the piston isapproaching bottom dead center during the power stroke;

FIG. 9 is an elevation showing the linkage of FIG. 6 when the piston isat bottom dead center;

FIG. 10 is a plan elevation taken on line 10-10 of FIG. 8; and

crank pin, and one end of the piston rod pivots relative to the pistonin the usual manner. The opposite ends of the crank pin extension linkand piston rod are pivotally connected together at a pivot point 18. Atoggle arm 10 is pivotally connected to the ends of the crank pinextension link and the piston rod at pivot point 18.

FIG. 11 is a plan elevation showing a concentric wrist pin arrangementfor use with the toggle linkages shown in FIGS. 1-5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 11, aconcentric wrist pin arrangement pivotally connects the piston rod,toggle arm, and crank pin extension link at pivot point 18. The end ofcrank pin extension link 8 forms a yoke 8a which is pivotally connectedto the end of piston rod 6 by an outer wrist pin 18a. The outer end oftoggle arm 10 forms a yoke 10a which fits around the outside of yoke 8aand is connected to piston rod 6 and crank pin extension link 8 by aninner wrist pin 18b which is fitted in the opening through outer wristpin 18a.

The piston is disposed above the crankshaft 3 in a cylinder 12 ofhousing 14. A spark plug 17 and valves 19 are disposed at the top of thecylinder 12, and these components function as in conventional internalcombustion engines. However, the cam lobes (not shown) have a differentarrangement than in conventional engines, because the crank pin 3 isdriven through a substantially greater arc during the power stroke ofthe piston thanthe crank pin of conventional engines, as will bedescribed in detail below. The toggle arm 10 has its stationary endpivotally secured to the housing 14 at a fixed point 16 adjacent to thecylinder. The point 16 is shown at the right side of the crankshaft 3 inFIGS. l-3. However, the point 16 can be located on the left side of thecrankshaft, as shown in FIGS. 4 and 5.

Preferably, points 18, 5, and 3 are collinear at the start of the powerstroke. The toggle arm 10 is longer than the crank pin extension link 8,and the crank pin extension link is longer than the radius of the crankthrow 2 and shorter than the diameter of the crank throw.

In use, during reciprocating movement of the piston, piston thrustcauses the toggle linkage to produce a toggle action so that pistonthrust is directed substantially tangentially to the crankshaft by thecrank pin extension link, to drive the crankshaft in a clockwisedirection, as indicated by the arrow in FIGS. l-3. The toggle arm 10maintains the tangential position of the crank pin extension link 8throughout a substantial portion of the power stroke of the piston. Inconventional engines, the linkage does not effectively transmit pistonthrust to the crank pin during the beginning and end portions of thepower stroke of the piston. The toggle linkage shown in FIGS. l-3improves the efficiency of power transmission from the piston to thecrank pin, when compared with conventional reciprocating engineoperation, because it applies tangential thrustto the crank pin duringthe beginning and end portions of the power stroke of the piston.

As the piston nears the end of the power stroke, as shown in FIG. 2, thecrank pin extension link 8 pivots in a clockwise direction away fromtoggle arm 10 to produce a pronounced forward toggle action on the crankpin which exerts a strong tangential force on the crank pin during theend portion of the power stroke. Thus, good power transmission isobtained, because the forward toggle action improves the torquedeveloped by the crankshaft during the low pressure portion of the powerstroke, when compared with conventional engmes.

As the piston travels through its bottom dead center position, thetangential force applied to the crank pin by the toggle linkage shown inFIGS. 1-3 causes the crank pin extension link to continue rotating in aclockwise direction away from the toggle arm 10, with the result thatthe crank pin travels substantially more than 180 during the powerstroke of the piston. During this portion of the cycle, relatively smalldisplacement of the piston drives the crankshaft through acorrespondingly large are, because inertial energy of the linkage isconverted to kinetic energy of the crank pin through the Iinkagestangential application of thrust.

The toggle arm travels through an angle of about 45 during reciprocatingmovement of the piston. The moving end of the toggle arm 10 moves closeto the center of the crankshaft. The toggle arm does not travel over thecenter of the crankshaft, because this would lock the mechanism. FIG. 2also shows a lubrication channel within the toggle arm 10 for use inlubricating pivot point 18.

Although the stationary pivot point 16 of the toggle arm 10 ispositioned to the right of the crankshaft in FIGS. l-3, it can bepositioned to the left of the crankshaft. FIGS. 4 and 5 show thestationary pivot point 16 located to the left of the crankshaft on animaginary line 16a extending through the center of the crankshaft. Withthis arrangement, the crank pin extension link 8 is similarly maintainedin a substantially tangential relation to the crankshaft 3 during thepower stroke. As above, force transmitted through the piston rod 6 tothe crankshaft 2 is directed substantially tangentially to thecrankshaft by the extension link 8 to drive the crankshaft in aclockwise direction, as indicated by the arrow in FIG. 4. The toggle arm10 maintains the tangential position of the crank pin extension link 8throughout the power stroke of the piston.

FIG. 5 shows the position of the linkage during the return stroke of thepiston. The crank pin extension link 8 has pivoted toward the toggle arm10 to produce an inverted toggle action" on the crank pin, with thecrank pin extension link exerting a force on the mutual pivot point 18that causes the piston to be returned to its closed position in anextremely fast action. The effective leverage ratio obtained is about l-/z to 1. Continued rotation of the crankshaft 2 then moves the linkagemembers into the position as shown in FIG. 4, for repetition of thecycle.

FIGS. 6 through 10 show an alternative toggle linkage which includes adouble wrist pin arrangement for connecting the ends of piston rod 6,crank pin extension link 8, and toggle arm 10. One end of the crank pinextension link 8 forms a yoke 21 which is pivotally secured to thepiston rod 6 by a first wrist pin 22. The outer end of the toggle arm 10forms a yoke 23 which fits around the outside of yoke 21. The toggle armyoke 23 is pivotally secured to the yoke 21 by a second wrist pin 24 ata point spaced from wrist pin 22 and laterally offset from the axis ofthe piston rod. The double wrist pin arrangements shown by way ofexample only, and other means for connecting the ends of the piston rod,crank pin extension link, and toggle arm in an eccentric arrangement canbe used without departing from the scope of the invention. For example,the inside-outside wrist pin arrangement shown in FIG. 3A can be made inan eccentric configuration to obtain a double wrist pin action. Such amechanism (not shown) includes a first yoke at the end of crank pinextension link 8 which is pivotally secured to the end of piston rod 6by an outside sleeve. The outer end of the toggle arm 10 forms a secondyoke which fits around the outside of the first yoke. The second yoke ispivotally secured to the first yoke. The second yoke is pivotallysecured to the first yoke by an inside sleeve which extends through theoutside sleeve along an axis which is offset from the axis of theoutside sleeve in the direction toward the crank pin. The outside sleeveis keyed to the crank pin extension link. This maintains the pivot pointof the piston rod away from the crank pin to produce increased leverageover the concentric double wrist pin arrangement.

Toggle arm 10 pivots about pivot point 16 which lies on a substantiallyhorizontal imaginary line 16b (FIG. 6) extending through the center ofthe crankshaft. In an alternative embodiment of the double wrist pinlinkage (not shown), toggle arm 10 can be mounted on the other side ofthe crankshaft above the crank throw. The point 16 also can be locatedabove or below the line 16b without significantly affecting theoperation of the linkage. The point 16 should not be located wheremovement of the piston would cause the toggle arm to travel over thecenter of the crankshaft and lock the mechanism.

The crank pin extension link 8 shown in FIGS. 6-10 is longer than theradius of the crank throw and shorter than the diameter of the crankthrow, and the toggle arm shown in FIGS. 6-10 is longer than the lengthof the crank pin extension link, and preferably longer than the diameterof the crank throw.

In use, during reciprocating movement of the piston, the toggle linkageshown in FIGS. 6-10 produces a walking beam action on the crank pinthrough the end portion of the return stroke and the beginning portionof the power stroke of the piston to produce a tangential thrust on thecrank pin as the piston passes through its top dead center positionshown in FIG. 6. The walking beam action blends into a toggle action onthe crank pin which produces a tangential thrust on the crank pin as thepiston travels through the beginning portion of the power stroke shownin FIG. 7. During the intermediate portion of the power stroke, fromFIG. 7 to FIG. 8, the toggle arm and crank pin extension link applythrust to the crank pin in the convention manner. During the end portionof the power stroke of the piston, from FIG. 8 to FIG. 9, continueddownward movement of the piston causes the crank pin extension link toswing back so as to rotate in a clockwise direction about wrist pin 22and toward toggle arm 10. This action causes the conventional thrust toblend into a toggle action on the crank pin which applies a tangentialforce to the crank pin as shown in FIG. 8. During the end portion of thepower stroke of the piston and the beginning portion of the returnstroke, the toggle action blends into a walking beam action whichproduces a tangential thrust on the crank pin as the piston passesthrough its bottom dead center position shown in FIG. 9. The crank pinis driven through an arc of approximately 245 during the power stroke ofthe piston, as shown in FIG. 9.

Thus, the linkage shown in FIGS. 6 through 10 blends together insequence walking beam action, toggle action, conventional action for ashort distance, toggle action, and walking beam action to producetangential thrust on the crankshaft so that the thrust developed by thepiston is effectively applied to the crankshaft throughout its entirepower stroke.

During the return stroke of the piston from the position shown in FIG. 9to the position shown in FIG. 7, inverted toggle action applied to thecrank pin extension link exerts leverage on the piston rod to rapidlyreturn the piston to top dead center.

The toggle linkage of this invention has the advantageover theconventional rod and crankshaft arrangement of distributing piston trustover a longer period of time during the power stroke,'because the crankpin is driven through an arc of greater than 180 during the power strokeof the piston. Thus, a longer burn time results during the power stroke,and greater breathing results during the intake stroke. Longer burn timealso has the advantage of obtaining a more complete combustion of fueldelivered to the engine cylinders, with the result that more enginepower is developed from a given amount of fuel than in conventionalengines. Furthermore, the longer burn time produces a lower temperatureof combustion which reduces the formation of oxides of nitrogen, whichin turn are a significant factor in causing air pollution.

Moreover, the toggle linkage provides more usable thrust during thepower stroke of the piston than convention reciprocating engines, whichhave substantial lost motion near top dead center and bottom dead centerduring the power stroke. The linkage of convention engines iseffectively locked in top dead center and bottomdead center, with theresult that a substantial portion of the piston thrust developed isdissipated in overcoming inertial and frictional forces in theconventional linkage. Piston thrust in conventional engines iseffectively taken advantage of only during the intermediate portion ofthe power stroke. Conventional engines are generally operated atrelatively high speeds to overcome the lost motion occurring at thebeginning and end portions of the power stroke of the piston. The lostmotion in the linkage of conventional engines at top dead center also isa contributing factor to undesirable detonation of fuel in thecylinders. The toggle linkage of this invention increases theeffectiveness of the piston thrust applied to the crank pin during thebeginning and near the end of the piston power stroke, when comparedwith conventional engines. This increased transfer of thrust to thecrankshaft develops more engine power, produces a smoother operatingengine, and substantially avoids detonation of fuel in the cylinders.

lclaim:

1. A reciprocating engine comprising a rotary crankshaft having a crankpin; a piston disposed in an engine cylinder and movable therein totransmit power to the crankshaft; and a connecting linkage fortransmitting power from the piston to the crankshaft, the connectinglinkage including:

a. a piston rod having one end pivotally secured to the piston;

b. an elongated crank pin extension link having one end pivotallysecured to the other end of the piston rod, the other end of the crankpin extension link being pivotally secured to the crank pin at a pointspaced from the axis of rotation of the crankshaft,

c. a toggle arm;

. means for pivotally connecting one end of the toggle arm with thecrank pin extension link at a point spaced from the crank pin by adistance greater than the radius of the crank throw and less than thediameter of the crank throw; and

e. means for pivotally securing the other end of the toggle arm to astationary pivot point spaced from the pivot at the other end of thetoggle arm by a distance greater than the diameter of the crank throw sothat the toggle arm transmits force between the piston and the crank pinthrough the piston rod and crank pin extension link in a substantiallytangential direction to the crankshaft during the power stroke of thepiston to drive the crankshaft through more than one-half a revolution.

2. Apparatus according to claim 1 wherein the means for pivotallyconnecting the end of the toggle arm to the crank pin extension linkcomprises a single wrist pin for connecting the ends of the toggle arm,crank pin extension link, and piston rod at a mutual pivot point.

3. Apparatus according to claim 1 wherein the ends of the crank pinextension link are substantially collinear with the center of thecrankshaft at the beginning of the power stroke.

4. Apparatus according to claim 1 wherein the effective length of thecrank pin extension link is about fiveeighths the diameter of the crankthrow, and the effective length of the toggle arm is about 1% times thediameter of the crank throw.

5. Apparatus according to claim 1 wherein the effective length of thetoggle arm is about ltimes the diameter of the crank throw; and whereinthe stationary pivot point of the toggle arm is located below the pistonon a substantially horizontal line through the center of the crankshaft.

6. A linkage for connecting the piston and the crank pin of a crankshaftin a reciprocating engine, the linkage comprising:

a. a piston rod having one end pivotally secured to the piston;

b. an elongated crank pin extension link having one end pivotallysecured to the other end of the piston rod by a first wrist pin, theother end of the crank pin extension link being pivotally secured to thecrank pin at a point spaced from the axis of rotation of a crankshaft;

c. a toggle arm;

. means for pivotally connecting one end of the toggle arm with thecrank pin extension link at a point spaced from the crank pin by adistance greater than the radius of the crank throw and less than thediameter of the crank throw, the connecting means comprising a secondwrist pin connect to the crank pin extension link between the firstwrist pin and the crank pin; and

e. means for pivotally securing the other end of the toggle arm to astationary pivot point spaced from the pivot at the other end of thetoggle arm by a distance greater than the diameter of the crank throw sothat the toggle arm transmits force

1. A reciprocating engine comprising a rotary crankshaft having a crankpin; a piston disposed in an engine cylinder and movable therein totransmit power to the crankshaft; and a connecting linkage fortransmitting power from the piston to the crankshaft, the connectinglinkage including: a. a piston rod having one end pivotally secured tothe piston; b. an elongated crank pin extension link having one endpivotally secured to the other end of the piston rod, the other end ofthe crank pin extension link being pivotally secured to the crank pin ata point spaced from the axis of rotation of the crankshaft, c. a togglearm; d. means for pivotally connecting one end of the toggle arm withthe crank pin extension link at a point spaced from the crank pin by adistance greater than the radius of the crank throw and less than thediameter of the crank throw; and e. means for pivotally securing theother end of the toggle arm to a stationary pivot point spaced from thepivot at the other end of the toggle arm by a distance greater than thediameter of the crank throw so that the toggle arm transmits forcebetween the piston and the crank pin through the piston rod and crankpin extension link in a substantially tangential direction to thecrankshaft during the power stroke of the piston to drive the crankshaftthrough more than one-half a revolution.
 2. Apparatus according to claim1 wherein the means for pivotally connecting the end of the toggle armto the crank pin extension link comprises a single wrist pin forconnecting the ends of the toggle arm, crank pin extension link, andpiston rod at a mutual pivot point.
 3. Apparatus according to claim 1wherein the ends of the crank pin extension link are substantiallycollinear with the center of the crankshaft at the beginning of thepower stroke.
 4. Apparatus according to claim 1 wherein the effectivelength of the crank pin extension link is about five-eighths thediameter of the crank throw, and the effective length of the toggle armis about 1- 1/2 times the diameter of the crank throw.
 5. Apparatusaccording to claim 1 wherein the effective length of the toggle arm isabout 1- 1/2 times the diameter of the crank throw; and wherein thestationary pivot point of the toggle arm is located below the piston ona substantially horizontal line through the center of the crankshaft. 6.A linkage for connecting the piston and the crank pin of a crankshaft ina reciprocating engine, the linkage comprising: a. a piston rod havingone end pivotally secured to the piston; b. an elongated crank pinextension link having one end pivotally secured to the other end of thepiston rod by a first wrist pin, the other end of the crank pinextension link being pivotally secured to the crank pin at a pointspaced from the axis of rotation of a crankshaft; c. a toggle arm; d.means for pivotally connecting one end of the toggle arm with the crankpin extension link at a point spaced from the crank pin by a distancegreater than the radius of the crank throw and less than the diameter ofthe crank throw, the connecting means comprising a second wrist pinconnect to the crank pin extension link between the first wrist pin andthe crank pin; and e. means for pivotally securing the other end of thetoggle arm to a stationary pivot point spaced from the pivot at theother end of the toggle arm by a distance greater than the diameter ofthe crank throw so that the toggle arm transmits force between thepiston and the crank pin through the piston rod and crank pin extensionlink in a substantially tangential direction to the crankshaft duringthe power stroke of the piston to drive the crankshaft through more thanone-half a revoluTion.